The invention disclosed herein pertains to a method and apparatus for regulating the pressure of the water in a closed water conducting circuit, downstream from a steam conducting circuit, which water circuit and steam circuit are both heated by a common source of heat.
Steam boilers may be heated with a waste heat carried by gases exhausted from a gas turbine. Because the temperature of these gases at the gas turbine stack outlet is often relatively high it is economically feasible to install a first heat exchanger, downstream from the steam boiler, by means of which a primary water may be heated. The primary water heated with the first heat exchanger may be circulated through a closed water conducting circuit which includes at least a second heat exchanger. The second heat exchanger can be used for heating various secondary fluids, for example, secondary water to be used in heating systems, and air. The heated primary water flows through the closed water conducting circuit which is arranged intermediate the gas turbine exhaust stack and the secondary fluid to be heated by the primary water.
The intermediate water circuit must be under pressure in order to avoid evaporation of the hot primary water. Because of the limited structural stability of the water conducting components of the intermediate water circuit, i.e., the limited structural stability of the pipes and heat exchangers, the pressure in the intermediate water circuit must not exceed a specified pressure. For this reason, a pressure regulating device must be provided which controls and limits the variation of the pressure in the intermediate circuit to within a specified range.
Accordingly, a primary object of the present invention is to utilize the waste heat from a gas turbine generator to heat a steam conducting circuit and a pressurized water conducting circuit, while avoiding structural damage to the water conducting circuit.
Yet a further object of the present invention is to regulate the pressure of the water in the pressurized water conducting circuit.
Apparatus for regulating the pressure of the water in a pressurized, closed water conducting circuit downstream from a steam conducting circuit, which steam circuit and water circuit are heated by a waste heat from a gas turbine generator, according to the present invention, includes a gas turbine generator, a steam circuit, and a pressurized water circuit. The steam circuit includes a steam boiler, a steam turbine generator, and a water tank with a degassing dome. The pressurized water circuit includes a heat exchanger downstream from the steam boiler, and an expansion tank which provides a volume expansion capacity for the water circuit. First and second water lines link the steam circuit to the water circuit. Valves in these water lines regulate a flow of water between the water circuit and the steam circuit. A pressure sensor senses the pressure of the water in the water circuit, and a valve regulator opens and closes the valves in the first and second water lines in response to signals from the pressure sensor.